Medical History: Blood tests exceeding any of the limits defined below will lead to exclusion from the study: ALT (SGPT) or AST (SGOT) is greater than three times the upper limit of normal; total white blood cell count is less than 3,000/mm(3), neutrophils less than 2,000; platelet count of less than 85, 000/mm(3); creatinine greater than 1.5 mg/dl; serology indicating HIV infection or active hepatitis A, B, or C infection; postive pregnancy test or breast-feeding female; nausea/vomiting as a frequent complaint; fasting prolactin levels of greater than 20 micrograms/L; history or signs of immunodeficiency; history of galactorrhea and/or history of prolactin-secreting tumors, history of pituitary tumors and adenomas, history of mammary tumors; clinically relevant arrhythmia or other ECG abnormalities.